In the viticultural field, a well-known practice is to prearrange vine support structures consisting of rows of poles driven into the ground so as to form rows of grapevines. The poles are spaced at regular distances and are connected at a certain height from the ground by at least one fixed horizontal wire, called “carrying wire” or “training wire”.
On the two poles located at the head of each row, called “head poles”, is also fastened at least one pair of parallel wires arranged on respective sides of each pole in the row. These wires are commonly called “containment wires” or “movable wires” because, during the different phases of cultivation of the plants, they are moved to different heights above the ground to contain and arrange the growing vegetation according to a desired configuration. This is a particularly laborious operation.
Italian Patent application PN2010A000023, filed by the same holders of the present application, describes a fastening device for the “movable wires” of a row of plants, in particular grapevines, which foresees connecting the movable wires to vertical guide elements associated to the end or head poles. The ends of the movable wires are fastened to mounting means that are inserted and can slide within the guides formed in the vertical guide elements, so as to modify the height of the movable containment wires and adapt it to the growing vegetation.
This solution is advantageous, but it does not offer the possibility of optimizing at another moment the position of the training wire and of the second wire, and of any third fixed wire, if present, that are located higher than the training wire having a support function. Moreover, it does not completely solve the problem of pruning the vine shoots after the grapes have been harvested. In effect, automatic machines have been built that move along the rows and are provided with means for lifting and cutting the vegetation. However, these machines cannot perform satisfactorily in the area at the head of the rows, that is in the area that goes from the head pole to the first plant support pole.
European Patent Application EP 2 324 700 A1 describes an elastic compensation device for the movable wires in viticultural systems. This device includes a first fastening element for connection to a head pole in the row and a second fastening element to receive at least one pair of movable wires. The first and the second fastening elements are interconnected by an elastic element and are both arranged at the same end of said elastic element, so as to apply only a compression force on the latter. Wire-tensioning means are also provided in opposite positions with respect to the elastic element to engage the pairs of containment wires and to make it possible to adjust their tension. However, the solution described in Patent Application EP 2 324 700 A1 is not adaptable to a “training wire” and is bound to the use of a specific tensioning means.